Fluid treatment apparatus



Oct. 16, 1962 J. N. CARMAN 3,058,478

FLUID TREATMENT APPARATUS Filed Oct. 9, 1959 2 Sheets-Sheet 1 INVEN TOR.

Jlgfzz? AZ Carma Oct. 16, 1962 J. N CARMAN 3,058,478

FLUID TREATMENT APPARATUS Filed Oct. 9, 1959 2 Sheets-Sheet 2 Q9 J J INVENTOR.

"1) fastzze M Karma rates This invention relates to apparatus for fluid treatment of a workpiece, for example for acid etching of a semiconductor crystal, and has for its objects the provision of apparatus which is adapted for rapid serial treatment of workpieces while confining the working fluid so that its fumes, for example, do not escape.

According to the invention fluid treatment apparatus comprises a tank adapted to be filled to a predetermined level, a fluid treatment device projecting above said level, a workpiece carrier movable past said device, said carrier having wall means extending below said liquid level to form therewith a closed chamber, and said carrier having a receptacle for holding a workpiece in said chamber, so that it may be moved past and treated by said device while confining the fluid in said chamber.

For the purpose of illustration typical embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a plan view of acid etching and washing apparatus, parts being broken away;

FIG. 2 is a section on line 22 of FIG. 1;

:FIG. 3 is an enlarged section on line 33 of FIG. 1;

FIG. 4 is a fragmentary bottom view showing etching and washing stations; and

FIG. 5 is an enlarged sectional view showing a modification of the apparatus of FIGS. 1 to 4.

The apparatus shown in FIGS. 1 to 4 comprises a water tank 1 having a drainpipe 2 which establishes a water level 3. The tank is supplied with circulating water whose temperature is preferably controlled at a constant value. Hinged to the tank 1 is a cover 4 including a hood 5. Entering through the bottom of the tank is a hollow column 6 on which is fixed a circular bracket 7. The bracket 7 holds a number of jet nozzles 8 at equally spaced angular intervals on a circular path extending most of the way around the bracket. The nozzles and bracket are submerged except for the tips of the nozzles.

Indexing clockwise within the column 6 is a shaft 9 on which a circular work carrier 11 is detachably seated and keyed. The shaft is indexed intermittently by a motor M acting through gears 12 and 13. The shaft and carrier are locked in adjusted position by a plunger 14 engaging a socketed wheel 16. The plunger is withdrawn from the wheel 16 by a solenoid K. A timer T periodically energizes the solenoid K and motor M, so as to index the carrier at repeated intervals, for example, at two secon intervals.

The workpiece carrier 11 has lower walls 17 which extend below the water level 3 and form with the surface of the water an annular chamber 18. The nozzles 8 extend into this chamber and are directed toward the upper portion of the lower walls. Opening into the chamber 18 are a number of sockets 1? for holding a workpiece Y, in this example a partially assembled diode having leads L and a crystal face opposite the tip of the nozzle 8. The socket includes an adaptor 20 closely fitting the diode. The adaptor 20 may be removed and replaced by different adaptors closely fitting variously shaped diodes or other workpieces. The sockets are distributed at equally spaced intervals which are equal to the intervals at which the nozzles 8 may be placed on the bracket 7. On its upper side the carrier 11 forms an annular trough 21 which, like the chamber 18, extends entirely around the carrier. The workpiece sockets extends from the trough 21 to the chamber 18, and during operation this connection is plugged by the workpiece. A water tube 22 is held by the hood 5 directly over the trough, and a constant slow tflow of water keeps the trough filled and, together with the workpiece, completely seals otf the chamber 18 from the atmosphere. When a workpiece is re moved, the vacated socket fills with water from the trough, the flow into the chamber being so short and slow that the water maintains the sealing of the chamber.

As shown in FIGS. 1 and 4, the nozzles 8 are disposed at stations I to IX extending part way around the bracket 7. The nozzles at the various stations are connected under water by tubes 23 leading to flow control valves 30 on manifolds 24-27 at the bottom of the tank 1. Tubes leading from sources of supply enter the respective manifolds 24 to 27 supplying them with liquids at a relatively constant pressure. These manifolds serve to distribute the liquid to one or more lines 23 through flow control valves 3%. In travelling through the tubes in the water in the tank 1 the fluids tend to take the same temperature as the tank water. The manifolds supply diiferent fluids such as acid, a quenching fluid such as hydrogen peroxide, water, alcohol, acetone, and air.

A typical junction etching treatment sequence would include at stations I and 11 exposure to a jet of hydrofluoric and nitric acid; at station III a quenching rinse of hydrogen peroxide; at stations IV to VIII successive water rinses; and at station IX an alcohol rinse. Between stations IX and I is an angular interval equivalent to three stations in which treatment stations are omitted to allow for removing the treated workpieces and replacing them with pieces to be treated. In this interval the carrier 11 is exposed through an opening 10 in the cover 4 just forward of the hood 5 (see FIG. 2). Through this opening 1% workpieces are placed in the sockets 2t}.

To prevent strong acid fumes released at stations I and II from circulating around the annular chamber 18 a counterflow current of air is introduced to the chamber 18 through a tube 28 which projects into the chamber just beyond the second acid station II. An exhaust tube 29 projects similarly just before the first etching station I. Air flows counterclockwise from tube 28 to tube 29 drawing acid fumes away from subsequent fluid treating stations.

Preferably all parts of the apparatus which are exposed to the concentrated fluids in the chamber 18 or the dilute aqueous solution which develops in the tank are formed of acid resistant material. For example, the parts above water such as the carrier 11, the adaptor 20, the tips of the nozzles 8, and the tubes 23, 28 and 29 are formed of a tetrafluoroethylene polymer sold under the registered trademark Teflon. The underwater parts, the tank 1, column 6, the shaft 9, the bracket 7, manifolds 24-27, valves 30 and like fittings are of stainless steel.

In some cases it may be desirable to use two or more nozzles at each station, for example, in treating a tran sistor which has a three dimensional, exposed surface as compared with the flat face of a diode. Such a station is shown in FIG. 5 wherein is shown a transistor Z having three leads L. The transistor Z is held in a special adaptor 2th: in a modified carrier 11a. The nozzles 8 are directed from opposite sides of the transistor Z to insure complete treatment of its exposed surface. As in the embodiment of FIGS. 1 to 4 the nozzles are mounted on a bracket 7. The water tube 22 delivers a slow flow of water into the trough 21 of the transistor carrier 20a.

The overflow of water from either of the troughs 2 1 of carriers 20 or Zita, and the small loss from the troughs when a workpiece is replaced produce a small refreshment and circulation of the water in the tank. This may be augmented by water supply through a conduit 31 controlled by a valve 32 connected to a source of water at even temperature. The rate of fluid delivered through the air supply tube 2.2 and the manifolds 24- to 27 may be similarly controlled.

Typical operation of the machine is as follows:

The timer T is set to index the carrier one station interval every one to three seconds. At a rate of one station per second each socket is exposed through the access opening for about two seconds during which time the operator places a new workpiece in the socket. The new workpiece is then indexed to the first and then the second acid etching stations in which it receives about a two second etch. If it were desired to increase the duration of etching to 10 seconds, additional nozzles at stations III to V would be connected to an acid manifold and the indexing rate changed to two seconds per station. The workpiece then passes stepwise to the subsequent quenching and rinsing stations and appears in the access opening 10 wherethrough it is removed from the carrier and replaced. As the workpiece is indexed to the first and subsequent stations successive new workpieces are placed on the carrier. This process is repeated at the rate of 1200 to 2400 workpieces per hour, requiring only that the operator initially connect nozzles at the desired stations and set the timer, then feed workpieces to the carrier.

Such rapid and convenient feeding is made possible as a result of the bottom sealing of the treatment cham ber 18 surrounding all the stations, and further through the sealing of the sockets by Water in the trough 2.1, while the acid station is isolated from subsequent stations by the counterfiow current of air. Thus there is no need for a fume hood and the operator may stand directly over the apparatus with full freedom for his manipulation.

It should be understood that the present disclosure is for the purpose of illustration only and that the invention includes all modifications and equivalents which fall with in the scope of the appended claims.

I claim:

1. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a workpiece above said level, so that it may be moved past and treated by said device While confining the fluid in said chamber.

2. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamher, and said carrier having a socket exending through the wall means and accessible outside the chamber for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber.

3. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a socket extending through the Wall means for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, said carrier forming a trough for holding water, and said socket interconnecting said trough and chamber, so that water in said trough seals said socket when a workpiece is not held therein.

4. Apparatus according to claim 3 characterized by a conduit for continuously supplying water to said trough.

5. Apparatus according to claim 3 wherein said carrier is rotatably mounted and said trough is in annular form.

6. Apparatus for fluid impelled acid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, an acid delivery nozzle projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a workpiece above said level, so that it may be moved past and treated by said nozzle While confining acid fumes in said chamher.

7. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, at least two fluid impelling devices disposed in said chamber and projecting above said level, at least one of said devices being an acid delivery nozzle, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a workpiece in said chamber above said level, so that it may be moved past and treated by said devices while confining the fluid in said chamber.

8. Apparatus according to claim 7 characterized by separate fluid control valves connected to the respective devices.

9. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, and means to introduce and withdraw air at respective sides of said device in said chamber.

10. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, at least two fluid treatment devices disposed in said chamber and projecting above said level, one of said devices being an acid delivery nozzle, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the Wall means for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, and means to introduce and means to withdraw air at respective sides of said acid nozzle, thereby to prevent acid fumes from flowing to the other of said devices.

11. Apparatus for impelled fluid treatment of a workpiece, comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a rotatable workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber and forming an annular trough for holding water, and said carrier having a plurality of sockets extending through the wall means and interconnecting said trough and chamber for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, and means to index said carrier successively to move said sockets to said device.

12. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a work piece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a work-piece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, and means to circulate water at an even temperature in said tank.

13. Apparatus for impelled fluid treatment of a workpiece comprising a tank adapted to be filled to a predetermined level, a fluid impelling device projecting above said level, a workpiece carrier above said tank movable past said device, said carrier having wall means extending below said level to form therewith a closed air chamber, and said carrier having a receptacle extending through the wall means for holding a workpiece above said level, so that it may be moved past and treated by said device while confining the fluid in said chamber, means to circulate water at an even temperature in said tank, and conduit means supplying fluid to said device, said conduit means being disposed entirely below said level.

14. Apparatus for acid etching of a workpiece comprising a tank adapted to be water filled to a predetermined level, a plurality of liquid delivery nozzles, a standard in said tank holding said nozzles at spaced stations on a circular path, conduits for supplying fluid to said nozzles, said conduits being disposed in said tanks entirely below said water level, a circular work carrier, means rotatably supporting said carrier over said path, said carrier having annular wall means extending below said water level to form therewith a closed air annular chamber around said stations and having sockets extending through said wall to receive said workpieces and hold them at least partly facing into the chamber above said level, and means to index said carrier to bring successive workpieces to each station.

15. Apparatus according to claim 14 wherein said conduits comprise at least one manifold, fluid control valves connected to the manifold, and tubes interconnecting said valves and said nozzles.

16. Apparatus for acid etching of a workpiece comprising a tank adapted to be water filled to a predetermined level, a plurality of liquid delivery nozzles, a hollow column extending through the bottom of said tank for holding said nozzles at spaced stations on a circular path, a circular work carrier, a shaft turning within said column and rotatably supporting said carrier over said path, said carrier having annular wall means extending below said water level to form therewith a closed air annular chamber around said stations and having sockets extending through said wall to receive said workpieces and hold them at least partly facing into the chamber above said level, and means to index said carrier to bring successive workpieces to each station.

17. Apparatus for acid etching of a workpiece comprising a tank adapted to be water filled to a predetermined level, a plurality of liquid delivery nozzles, a standard in said tank holding said nozzles at spaced stations on a circular path, a circular work carrier, means rotatably supporting said carrier over said path, said carrier having annular wall means extending below said water level to form therewith a closed air annular chamber around said stations and having sockets extending through said wall to receive said workpieces and hold them at least partly facing into the chamber above said level, means to index said carrier to bring successive workpieces to each station, and air supply and air outlet means disposed respectively at each side of at least one of said stations to evacuate fumes of the liquid delivered at said station.

18. Apparatus for acid etching of a workpiece comprising a tank adapted to be water filled to a predetermined level, a plurality of liquid delivery nozzles, a standard in said tank holding said nozzles at spaced stations on a circular path, a circular work carrier, means rotatably supporting said carrier over said path, said carrier having annular wall means extending below said water level to form therewith a closed air annular chamber around said stations and having sockets extending through said wall to receive said workpieces and hold them at least partly facing into the chamber above said level, and means to index said carrier to bring successive workpieces to each station.

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